What is Cast Iron? Complete Explanation

Introduction

铸铁是在公元前5世纪在中国发明的。它几乎在世界各个角落使用。无论是汽车行业，建筑行业，制造业，管道行业等，都可以使用铸铁。在本文中，您将了解什么是铸铁，其类型，应用，其生产方式等。因此，让我们从其定义开始。

定义

它是一组铁碳合金，其中碳含量范围为2％至4％，硅含量为1％至3％，以及磷和硫磺等小杂质。如果铁合金中的碳含量小于2％，则称为钢。

特性of Cast Iron

脆：铸铁除了可延展的铸铁外是脆弱的。脆性的意思是，锤击时它会分解成小块。
低熔点：它具有低熔点（1127 - 1204摄氏度）
Fluidity:It possesses good fluidity ( The ability to flow easily in a molten state)
铸造性：It possesses good castability. Castability is defined as the ability to be cast into new parts in the casting process.
可加工性：它具有良好的可加工性。可加工性被定义为金属的能力，该金属允许以低成本的良好表面饰面轻松切割（加工）。
Resistance to deformation and wear resistance:It has excellent resistance to deformation i.e. it does not changes its shape when force is applied to it. It also has wear resistance which means that it opposes the damage in normal usage.

铸铁的熔点

铸铁范围在1127至1204摄氏度之间的熔点

What is Cast Iron Made up of ?

Cast iron is an alloy of iron and carbon in which the carbon is present in the range of 2-4 % by wt and silicon is present in between 1-3 % by wt. Some Other alloying elements that added to cast iron are manganese, molybdenum, chromium, magnesium, titanium, vanadium, nickel, copper, tin, zirconium, bismuth, boron. The alloying elements are added in order to control the percentage of the carbon and silicon as well as to give desired properties to the cast iron. the percentage of the carbon and silicon decides which type of cast iron is produced.

低硅允许碳sta的百分比y in the solution and forms carbide result in the formation of white cast iron. High Percentage forces carbon to remain out of the solution and results in the formation of graphite and Gray cast iron

The effect of adding different alloying elements in the molten pig iron is

Manganese, chromium, molybdenum, titanium, and Vanadium:它们反对硅对其进行中和，支持从溶液中吸收碳并形成各自的碳化物。
Magnesium:它有助于形成结节性（球形）石墨。
镍：It helps in refining the pearlite and graphite structure, and improving toughness
Copper:它降低了寒冷，增加流动性并完善石墨结构。
锆：It helps in the formation of graphite, acts as a deoxidizer, and increases fluidity.
钒：Stabilize cementite, increases hardness and resistance to wear and heat of cast iron
铋：将其添加到可延展铁的熔体中，以增加添加硅的程度。
锡：它可以添加为替代品代替铬。

另请阅读：

How Cast Iron is Produced

cast iron (CI)is produced from the pig iron. And pig iron is produced by melting iron ore in a blast furnace. The pig iron is converted into ingots and then these ingots are remelted again to produce cast iron. CI can also be produced directly from the molten pig iron.

种类Cast Iron

By Controlling the percentage of carbon and silicon in the molten pig iron and adding alloying elements we can get different types of cast iron. And these are

白铸铁

这是一种铸铁，含有3.4％的碳，1.5％的硅和.5％的锰。它被称为白铸铁，因为它在骨折时显示出白色裂缝。它是铸铁家族中唯一没有石墨的成员。它主要由碳化铁组成，其微观结构使其变得困难和脆弱。它是由熔融生铁的快速冷却产生的。

特性

这是坚硬而脆弱的。
不能轻松加工。
由于没有石墨，它的外观很轻。
它具有较高的抗压压力ngth and it also retains its hardness and strength even at high temperatures.
良好的耐磨性。

应用

它用于制作磨损表面，例如叶轮和浆液泵的玻璃表面，
在球磨坊中，它用来制作壳衬里和举重杆。
In coal pulverizers, it used to make balls and rings.
在挖掘机中，挖掘桶的牙齿是用白色铸铁制成的。

2. Grey Cast Iron

When molten pig iron in the presence of alloying elements is cooled moderately or slowly, we get grey cast iron. It has graphitic (i.e. graphite flakes is present in it) microstructure and shows grey color cracks when fractured. Due to the formation of grey cracks, it is named as grey cast iron. It is the most widely used cast iron based on weight among all types. If molten pig iron is cooled on a moderate rate then we get pearlitic gray cast iron and cooling on slow rate gives us ferritic gray cast iron.

另请阅读：

特性

low tensile strength
它具有良好的刚度。
It has high thermal conductivity and specific heat capacity.
由于存在石墨薄片，因此易于机加工。
Good damping capacity that allows it to used as the base for the machine tool mountings

应用

由于其刚度，它被用来使内燃烧缸块的外壳引擎，住房泵，阀体，装饰铸件和电盒。
It has high thermal conductivity and specific heat capacity that make it perfect to make盘式制动器rotors and cast iron cookware.
It is used as a base for machine tool mountings because of its very good damping capacity.

3.可延展的铸铁

Malleable cast iron is produced from the white cast iron. The white cast iron is heat-treated (Annealing) at about 950 Degree Celsius for 24 or 48 hrs and then allow to cool for 24 hrs or 48 hrs. This changes the carbon in the iron carbide of the cast iron into graphite and ferrite plus carbon. Nodular graphite is present in the malleable cast iron.

特性

It has excellent strength and toughness.
Very ductile and malleable in nature.

应用

Due to its excellent ductility and tensile strength, malleable CI is used for making electrical fittings and equipments, pipe fittings, hand tools, washers, farm equipment, brackets, mining hardware, parts of machines.

4. Ductile Cast Iron

延性铸铁在其微结构中具有结节性（球形）石墨。它也称为结节铸铁，球形石墨铸铁。基思·米利斯（Keith Millis）在1943年发现了延性铸铁。

Ductile cast iron is produced by adding nodulizing agent Magnesium in the molten pig iron that helps to convert graphite into nodules. Cerium, Tellurium, and Yttrium are also possible nodulizer that can be used.

特性

大多数延展性铸件与可延展的铸铁具有相似的特性。
It has good impact and fatigue resistance due to the presence of nodular graphite.

应用

它用于生产用于水和下水道线的延性铁管。
Automotive industry:它用来制造许多汽车组件，例如连杆，曲轴，气缸，盘式制动卡钳，齿轮和齿轮和变速箱等等
风力发电行业：在风能行业中，它用于制造轮毂和结构零件，例如机器框架。

可以焊接铸铁吗？

When a part of the cast iron gets broken, and its replacement requires a high amount of money then we think to repair it through welding. But the welding of the cast iron is a challenging task. The welding of cast iron is not as easy as welding steels. It requires extensive care and highly skilled welder. It can be welded if you know the type of cast iron you are going to weld.